1. Field of the Invention
The present invention relates to a viewing angle compensation field of a liquid crystal display, and more particularly to a wide viewing film and a wide viewing thin-film-transistor liquid-crystal-display (TFT-LCD) having the same.
2. Description of Related Art
The thin film transistor liquid crystal display (TFT-LCD) is one of the liquid crystal displays, and mainly uses the thin-film-transistor technology to improve the image quality. General speaking, the TFT-LCD can be regarded as two glass substrates and a liquid crystal layer disposed between the two substrates. The upper glass substrate is a color filter, and a lower substrate is provided with thin-film transistors. When current pass through the transistors, the electric field is changed such that the liquid crystal molecules are tilted so that the polarizing polarity of the light are changed. At the same time, polarizing film can be provided to change a bright and dark status of pixels in order to control the emitting of polarized light of each pixel in order to achieve an expected display.
In the conventional art, the problem is that after back lights pass through the polarizing film and TFT, the outputted lights has directionality. That is, most of light is perpendicularly emitted out from a screen. Accordingly, when viewing the LCD with a larger angle, the original color cannot be seen. Even, only full white or full black can be observed. FIG. 1 is a relationship among a white picture brightness, chromaticity and viewing angle, as shown at a left drawing of FIG. 1, when the brightness at an observation direction is decreased to one third of the brightness at a normal line direction, the viewing angle is less than 100 degrees. At the same time, when the when the brightness at an observation direction is decreased to one half of the brightness at a normal line direction, the viewing angle is smaller. Two drawings at right side of FIG. 1 are respectively chromaticity coordinates in an X direction (a horizontal direction) and in a Y direction (a vertical direction). As shown in the two drawings, the color shift at a large viewing angle is more serious.
Besides, along with the demand for the quality of the image of the display, the requirement for the LCD is higher. For example, the LCD becomes larger and larger so that many people watch a same TV such that the viewing angle of the LCD should be widen. Therefore, developing a technology for widening the view angle of the LCD is urgent.